Somebody on TVTropes' Villain Whitewashing* page ("other to B") wins an internet. (You'll have to click to enlarge it to read it. Sorry.)
I've actually thought about this aspect of Cthulhu (SURPRISE!) before. People always depict Cthulhu as just eating everything, but that's not really right; he wants to recruit humanity (regardless of whether humanity wants to be recruited or not-and if he succeeds, humanity will change to his way of thinking). If it weren't for the fact that the World Under Cthulhu is fairly explicitly a sort of orgiastic murder-revel, it wouldn't necessarily be actually bad at all.
*Making someone bad look good, not the other kind of whitewashing. ...It bore saying.